Restraints are utilized within automotive vehicles to prevent injury to vehicle occupants in the event of a collision. Various types of restraints are utilized, which may be active or passive in design. Some example active restraints are airbags, pretensioners, and load limiting seat belts. Some example passive restraints are seat belts, headrests, and energy absorbing material containing devices.
To satisfy various automobile safety requirements, such as the requirements under the Federal Motor Vehicle Safety Standard (FMVSS) 208, automobile manufacturers are required to include “Smart” airbag systems in their vehicles. Smart airbag systems refer to airbag systems that are capable of protecting occupants with different occupant characteristics, such as size, weight, and position within a vehicle seat. These requirements also require the prevention of airbag deployment when unwarranted. For example, it is undesirable to deploy an airbag into a rearward facing child seat or when a vehicle occupant is positioned too close to the airbag. To determine occupant characteristics, sensors, such as vehicle interior cameras and seat-based sensors, have been utilized. Such occupant characteristic sensors are considered impractical for certain applications and tend to complicate a restraint control circuit.
As an alternative to the use of occupant characteristic or classification sensors, airbag internal sensors are currently being introduced for determining the state of an airbag including the deployment characteristics thereof. Occupant characteristic information can be obtained or derived from the deployment characteristics. For example, by monitoring the deployed pressure of an airbag one can determine whether the airbag has collided with an object, such as a child seat. When the airbag collides with the child seat an uncharacteristical deployment pressure transient results as compared to a normal deployment defined as when the airbag is deployed without object intervention. A restraint controller may react in response to the uncharacteristical transient to prevent further expansion of the airbag.
Airbags with internal sensors are considered smart airbags. Smart airbags are distinguishable from smart airbag systems. Smart airbags are capable of determining a current state of an airbag whereas smart airbag systems are capable of altering the manner in which an airbag is deployed, depending on occupant determined characteristics.
There is a desire for traditional style airbags to be replaced with smart airbags and in addition that the introduction of the smart airbags not require changes to the traditional style restraint control systems or to the logic of any restraint controllers therein. It is also desired that upon the introduction of the smart airbags that existing restraint controllers be capable of determining when a fault exists with the smart airbag. A fault may include a static physical fault, such as one with a connector, a wire, and a trigger, as well as a dynamic physical fault, such as an uncharacteristical deployment condition.
Thus, there exists a need for a smart airbag that may be utilized in replacement of a traditional style airbag that does not require alteration to a corresponding restraint control system and that provides an indication to a restraint controller when a fault exists.